1. Field of Technology
The present invention relates to a check multifeed detection apparatus for use in a check processing terminal and a multifeed detection method.
2. Description of Related Art
Payment systems using checks are widely used throughout Europe and North America, Asia (worldwide). This payment system enables businesses and consumers to use checks to make payments and financial transfers of many kinds. When a check is written, it is ultimately presented to the bank on which the check was drawn to either deposit or withdraw funds.
Bank tellers at each bank branch typically process many checks in a short time. The bank teller also typically confirms check validity, the check date, and the signature before completing the deposit or withdrawal. The teller also prints an endorsement on the back, and issues a transaction receipt as required. The teller may also require a driver license or other photo ID to check the identity of the person presenting the check, and in some situations may make a photocopy of the license or photo ID using a copying machine. A copy of the check is also captured and stored using a specialized check scanner.
Efforts to electromagnetically read information from checks have started in order to provide more efficient check processing. Part of this process is to electromagnetically read each check at the teller window using compact check processing terminals that can be installed at each teller window.
These check processing terminals have a magnetic ink character reader (MICR), scanner, and printing mechanism disposed along the check transportation path. When a check is received from a customer, the teller passes the check through the check processing terminal. The check processing terminal thus reads the magnetic ink characters printed on the check, captures an image of the check, and may print an endorsement on the back. See, for example, Japanese Unexamined Patent Appl. Pub. 2000-344428.
A common problem of check processing terminals with this type of medium transportation path is that two or more checks may unintentionally be conveyed simultaneously along the transportation path. This is called “multifeed,” and the problem is inherent.
To solve this problem, Japanese Patent 3421104 teaches a multifeed detection apparatus having a reflection sensor located near the paper guide defining the form transportation path. This reflection sensor detects light reflected by the surface of the transported medium to directly detect the thickness of the paper and thereby detect check multifeeding.
Japanese Unexamined Patent Appl. Pub. S60-144256 also teaches a multifeed detection apparatus having a lever disposed to the roller shaft of the paper transportation roller to detect multifeeding by using optical sensors, for example, to detect displacement of the lever due to the paper thickness.
A multifeed detection apparatus having such a lever is described more specifically below with reference to FIG. 8.
The multifeed detection apparatus 100 shown in FIG. 8 has a detection lever 123 and a photodetector 140. The detection lever 123 is disposed on end portion 122 of rotary shaft 105a, which supports a pair of transportation rollers 105. This detection lever 123 is pivotably displaceable on a pivot shaft 124 disposed to one end portion 123c of the detection lever 123, is urged downward as seen in FIG. 8 by a tension spring 125 hooked on a protrusion 123a, and the force of this spring 125 holds the detection lever 123 applying downward pressure on the end portion 122 of the rotary shaft 105a. The other distal end 123b of the detection lever 123 is thus located adjacent to the photodetector 140, and the photodetector 140 detects displacement of this distal end 123b of the detection lever 123.
When paper passes below the transportation rollers 105, the transportation rollers 105 and rotary shaft 105a are pushed upward according to the thickness of the paper. The rotary shaft 105a therefore also pushes the detection lever 123 up in resistance to the force of the spring 125 while the paper passes below the transportation rollers 105. The photodetector 140 detects this displacement of the detection lever 123, and the paper thickness can then be detected based on the displacement of this detection lever 123.
When the multifeed detection apparatus taught in Japanese Unexamined Patent Appl. Pub. 2000-344428 is used, the thickness difference between one and two sheets is extremely small, and the detection sensitivity of the reflection sensor used to detect light reflected from the medium must be sufficient to detect this slight difference.
Furthermore, when the multifeed detection apparatus that detects the displacement of the rotary shaft of the transportation rollers as taught in Japanese Patent 3421104 is used, the transportation rollers become compressed over time due to the applied pressure, or the center of the transportation rollers may become offset from the center of the rotary shaft so that the rollers turn eccentrically. The reference position of the rollers thus shifts, and the paper thickness cannot be accurately detected.
The present invention is therefore directed to the aforementioned problems, and an object of the present invention is to provide a multifeed detection apparatus capable of accurately detecting multifeed situations by means of a simple design, and to provide a hybrid processing apparatus having this multifeed detection apparatus.